Application Of Static Probes And Throttling Nozzle

Static pressure fluctuation is an important factor in the momentum conservation of turbulent boundary layer. The throttle nozzle is widely used in engineering applications of throttling device, so it has a very important practical significance to study static probes and throttle nozzle.It has a significant impact on probe measurement performance that double-disc probe’s chamfer structure, sensor port’s diameter and internal boss, etc. Firstly, the impact of each part of the probe’s structures is analyzed through numerical simulation. Simulation results show that the performance of probe is more conducive than rounding probe when the discs structure using chamfer structure. C hamfering type structure can red uce clogging effect of the stagnation pressure due to the thickness of discs when the flow encounters disc. When the diameter of sensor port is 2mm, its structure is not only to meet the performance requirements of the probe, but also to overcome the static measurement of harsh environmental requirements. This Double-Disc probe has the desirable features of omnidirectional response and small error in pitch of ±20o. The boss structure at the center of the lower disc is an effective way to improve the measurement accuracy.Probe’s velocity and direction characteristics are calibrated referring to the principle of the probe calibration experiments, and set up a wind tunnel experiments with the outlet velocity is 0 ~ 30m/s. Speed calibration experiments show tha t the Double-Disc probe deviation increases with the wind speed increases. When the wind speed reaches 30m/s, maximum static pressure deviation reaches 7.95 Pa, and it is consistent with the results of simulation. Directional characteristic calibration expe riments show that when the wind speed reaches 30m/s, the Double-Disc probe has good directional characteristics in the pitch angle range of ±20°, and the static pressure variation can be maintained at ± 15 Pa. When the wind speed is less than 15m/s, Double probe has good directional characteristics in the pitch angle range of ±30°, and static pressure variation can be maintained within the range of ±20Pa. This probe has a good transient response characteristic under different wind speeds and it can meet application requirements.In the designation of throttle nozzle, firstly using an improved venturi nozzle type lines on the basis of calculated design methods, but this method proved there is a big error. The experimental data proved that selecting RNG k-ε turbulence model is accurate when to simulate the nozzle flow lines such as the larger degree of bending flow of the throttling device. The error is controlled in the tolerance the numerical simulation in the range of 10%. Finally, using the numerical simulation method to improve the nozzle-type lines, and it is proved the nozzle design meet the design requirements through experimental verification.